Ormula was determined as C13H18O4 by means of HRESIMS, establishing an index of hydrogen deficiency of five. The NMR information suggested BRPF3 Accession structural similarity with compound 1. However, compound 2 lacked the olefinic proton at H 6.90, which was replaced by three aliphatic protons (H 1.79, 2.43, and 2.91). These information recommended a distinction in between 1 and 2 of a double bond, as supported by a two amu difference within the HRMS data. The 1H NMR information of 2 revealed the presence of four olefinic protons, corresponding to two trans-disubstituted olefins (H five.52, ddq, J = 15.five, eight.0, 1.7; 5.55, ddq, J = 15.5, 5.2, 1.7; 5.91, dqd, J = 15.five, six.9, 1.7; and five.99, dq, J = 15.5, six.9, for H-1, H-1, H-2, and H-2, respectively), 4 oxymethines (H 3.48, dd, J = 12.0, 8.6; three.84, bq, J = 2.9; 4.03, ddd, J = five.2, 2.9, 1.7; and 4.67, dd, J = 8.6, 8.0, for H-7a, H-3, H-2, and H-7, respectively), 1 methine (H two.91, ddd, J = 12.6, 12.0, 3.four, for H-4a), a single methylene (H 1.79, ddd, J = 13.2, 12.six, two.9; and 2.43, ddd, J = 13.two, 3.four, two.9, for H-4 and H-4, respectively), two equivalent methyls (H 1.77, dd, J = 6.9, 1.7, for H-3 and H-3), and one exchangeable proton (H 1.84, for 3-OH). The 13C NMR data revealed 13 carbons, consistent using the HRMS data and indicative of one particular carbonyl (C 173.5 for C-5), 4 olefinic carbons (C 125.7, 126.four, 130.six, and 134.three, for C-1, C-1, C-2, and C-2, respectively), 5 methines (C 39.0, 66.3, 81.two, 82.1, and 82.four for C-4a, C-3, C-2, C-7a, and C-7, respectively), one particular methylene (C 30.0 for C-4), and two methyls (C 18.1 and 18.2 for C-3 and C-3, respectively) (see Supplementary Figures S3 and S4 for the 1H and 13C NMR spectra and Table S1). The two double bonds plus the carbonyl group accounted for 3 degrees of unsaturations, leaving the remaining two accommodated by the bicyclic ring technique. COSY data identified a single spin technique as H3-3/H-2/H-1/H-2/ H-3/H2-4/H-4a/H-7a/H-7/H-1/H-2/H3-3 (Figure 2a). The following essential HMBC NOD-like Receptor (NLR) supplier correlations had been observed: H3-3C-1, H3-3C-1, H-2C-2, H-7C-2, H-3C-4a, H-7aC-4, H-4aC-7, and H-4aC-5 (Figure 2a). NOESY correlations from H-1 to H-7a, from H-7a to H-2, and from H-2 to H-3 and H-2 indicated that H-1, H-7a, H-2, H-3, and H-2 were all on the identical face. Alternatively, NOESY correlations observed from H-4a to H-7 indicated that these two protons had been on the exact same side of the molecule but opposite to the preceding set (Figure 2b). Comparing all of these data with those for 1 yielded the structure of 2 (Figure 1), which was ascribed the trivial name transdihydrowaol A. The absolute configuration of 2 was assigned by way of a modified Mosher’s ester system,17 establishing the configuration as 2R, 3R, 4aR, 7S, and 7aR (Figure 3).18 Compound three (1.45 mg) was obtained as a colorless oil.19 The molecular formula was determined as C13H18O4 through HRESIMS, and was exactly the same as compound 2. The NMR information (Table S1 and Figures S5 and S6) suggested structural similarity with 2. Crucial variations were a coupling continuous of 0.6 Hz involving H-4a (H two.58, ddd, J = 7.five, two.3, 0.6) and H-7a (H 4.17, dd, J = 4.6, 0.six) in 3 vs 12 Hz in 2, as well as a NOESY correlation from H-4a to H-7a in three vs H-4a to H-7 in two (Figure 2d). These data implied a pseudoaxial/pseudoequatorial cis orientation of H-4a/H-7a. NOESY correlations had been also observed from H-2 to H-7a and H-4a, and from H-4a to H-3, indicating that these protons have been around the similar face (FigureTetrahedron Lett. Author manuscript; accessible in PMC 2014 August 07.NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-P.